Hereinafter, a system that has at least one cryptographic key stored in memory, whether or not a component in the system is using the key, is interchangeably referred to as simply “cryptographic system” unless expressly disambiguated where used. For example, a cryptographic system may simply hold a cryptographic key in memory for another system. As another example, a cryptographic system may store a cryptographic key in memory and allow a storage device mounted in the same system to use the stored cryptographic key.
A side channel attack is an attack on the physical machine of the cryptographic system. In other words, an attacker physically touches, comes in close proximity, or otherwise gains physical access (not over a data network) to a physical component physically connected to the machine or inside the machine.
A cold boot attack is an example of a side channel attack. Cold boot attacks against cryptographic systems involve acquiring physical access to a computer containing secured data while that data is in memory, applying low temperatures to the memory device—e.g. the Random Access Memory (RAM) modules, and then either rebooting the system using a specialized boot device to read the cryptographic keys from the cooled memory device, or removing the memory device while still cold from the cryptographic system and installing the cold memory device in a malicious system designed to read the contents from the cold memory device.